linux-kernel - Re: [PATCH v2 16/16] ARM64: XEN: Initialize Xen specific UEFI runtime services

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Message-ID: <alpine.DEB.2.02.1601181736090.9400@kaball.uk.xensource.com>
Date:	Mon, 18 Jan 2016 17:45:24 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Mark Rutland <mark.rutland@....com>
CC:	Shannon Zhao <zhaoshenglong@...wei.com>,
	<ard.biesheuvel@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<stefano.stabellini@...rix.com>, <david.vrabel@...rix.com>,
	<catalin.marinas@....com>, <will.deacon@....com>,
	<julien.grall@...rix.com>, <xen-devel@...ts.xen.org>,
	<devicetree@...r.kernel.org>, <linux-efi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <shannon.zhao@...aro.org>,
	<peter.huangpeng@...wei.com>, Jan Beulich <JBeulich@...ell.com>,
	Ian Campbell <Ian.Campbell@...rix.com>
Subject: Re: [PATCH v2 16/16] ARM64: XEN: Initialize Xen specific UEFI runtime
 services

On Mon, 18 Jan 2016, Mark Rutland wrote:
> On Fri, Jan 15, 2016 at 02:55:29PM +0800, Shannon Zhao wrote:
> > From: Shannon Zhao <shannon.zhao@...aro.org>
> > 
> > When running on Xen hypervisor, runtime services are supported through
> > hypercall. So call Xen specific function to initialize runtime services.
> > 
> > Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
> > ---
> >  arch/arm/xen/enlighten.c |  5 +++++
> >  arch/arm64/xen/Makefile  |  1 +
> >  arch/arm64/xen/efi.c     | 36 ++++++++++++++++++++++++++++++++++++
> >  drivers/xen/Kconfig      |  2 +-
> >  include/xen/xen-ops.h    |  1 +
> >  5 files changed, 44 insertions(+), 1 deletion(-)
> >  create mode 100644 arch/arm64/xen/efi.c
> > 
> > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> > index 485e117..84f27ec 100644
> > --- a/arch/arm/xen/enlighten.c
> > +++ b/arch/arm/xen/enlighten.c
> > @@ -414,6 +414,11 @@ static int __init xen_guest_init(void)
> >  	if (xen_initial_domain())
> >  		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
> >  
> > +	if (IS_ENABLED(CONFIG_XEN_EFI)) {
> > +		if (efi_enabled(EFI_PARAVIRT))
> > +			xen_efi_runtime_setup();
> > +	}
> > +
> >  	return 0;
> >  }
> >  early_initcall(xen_guest_init);
> > diff --git a/arch/arm64/xen/Makefile b/arch/arm64/xen/Makefile
> > index 74a8d87..62e6fe2 100644
> > --- a/arch/arm64/xen/Makefile
> > +++ b/arch/arm64/xen/Makefile
> > @@ -1,2 +1,3 @@
> >  xen-arm-y	+= $(addprefix ../../arm/xen/, enlighten.o grant-table.o p2m.o mm.o)
> >  obj-y		:= xen-arm.o hypercall.o
> > +obj-$(CONFIG_XEN_EFI) += efi.o
> > diff --git a/arch/arm64/xen/efi.c b/arch/arm64/xen/efi.c
> > new file mode 100644
> > index 0000000..33046b0
> > --- /dev/null
> > +++ b/arch/arm64/xen/efi.c
> > @@ -0,0 +1,36 @@
> > +/*
> > + * Copyright (c) 2015, Linaro Limited, Shannon Zhao
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program.  If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include <linux/efi.h>
> > +#include <xen/xen-ops.h>
> > +
> > +void __init xen_efi_runtime_setup(void)
> > +{
> > +	efi.get_time                 = xen_efi_get_time;
> > +	efi.set_time                 = xen_efi_set_time;
> > +	efi.get_wakeup_time          = xen_efi_get_wakeup_time;
> > +	efi.set_wakeup_time          = xen_efi_set_wakeup_time;
> > +	efi.get_variable             = xen_efi_get_variable;
> > +	efi.get_next_variable        = xen_efi_get_next_variable;
> > +	efi.set_variable             = xen_efi_set_variable;
> > +	efi.query_variable_info      = xen_efi_query_variable_info;
> > +	efi.update_capsule           = xen_efi_update_capsule;
> > +	efi.query_capsule_caps       = xen_efi_query_capsule_caps;
> > +	efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
> > +	efi.reset_system             = NULL;
> > +}
> 
> How do capsules work in the absence of an EFI system reset?

Actually I don't think that capsules are available in Xen on ARM64 yet,
see "TODO - disabled until implemented on ARM" in
xen/common/efi/runtime.c.

FYI system reset is available, but it is provided via a different
mechanism (HYPERVISOR_sched_op(xen_restart...)


> Are there any other mandatory features that are missing in a
> Xen-provided pseudo-EFI?